Beastie, mascot of BSD operating system

The BSD daemon's nickname Beastie is a slurred phonetic pronunciation of BSD. Beastie customarily carries a trident to symbolize a software daemon's forking of processes.

The artwork has a life before BSD. Phil Foglio draw the first version for Unix book. In 1984 John Lasseter redraw it (the original was lost somewhere at DEC) for the "Unix System Manager Manual".
IT was use again in 1988 for "The Design and Implementation of the 4.3BSD Operating System." a book from Marshall Kirk McKusick (he own the copyrights on Beastie).

Then in 1994 BSD used Beastie as a mascot/logo.

Duke, mascot of Java Language

Duke was created is the early development of Java, for one of the first demo on s Star7 handheld device.

"Duke was actually a representation of the "software agent" that performed tasks for the user. The device that contained the user interface was called *7 (pronounced "star seven"), after a feature of the phone system in the Green Team's office."

Important notes :
Duke is LeftHanded.
Duke is under BSD licence, since 2006.

Mozilla, mascot of Mozilla Foundation

Mozilla was the mascot of the now disbanded Netscape Communications Corporation and subsequently the Mozilla Foundation.
Mozilla took the form of a green and purple cartoon lizard. Programmer Jamie Zawinski came up with the name during a meeting while working at the company. Mozilla was designed by Dave Titus in 1994.
The name "Mozilla" was already in use at Netscape as the codename for Netscape Navigator 1.0. The term came from a combination of "Mosaic killer" (as Netscape wanted to displace NCSA Mosaic as the world's number one web browser) and Godzilla. Initially the mascot took various forms, including that of a helmeted astronaut or "spaceman", but the eventual choice of a Godzilla-like lizard was no doubt thought to go well with the Godzilla-like name.

Tux, mascot of Linux Kernel

Tux is a penguin character and the official mascot of the Linux kernel.

Originally created as an entry to a Linux logo competition, Tux is the most commonly used icon for Linux, although different Linux distributions depict Tux in various styles. In video games featuring the character female counterparts, named Penny and Gown, accompany him. The character is used in many other Linux programs and as a general symbol of Linux.

Hexley, mascot of Darwin

Hexley is the mascot for Apple's open source operating system Darwin. This mascot had its genesis on the Darwin-Developers mailing list. Various proposals were put forward by the members of the list, and after much lively discussion everyone settled on a Platypus.

"Hexley was created in response to a query on the Darwin Developers mailing list that they needed a mascot. This was sometime in the year 2000. A web vote was taken of the various submissions and my platypus was chosen. Some of the other submissions included an Aqua Darwin fish and various devilish modifications of Clarus the Dogcow."

Unfortunally, Darwin has never been well know, so was Hexley, but its a nice character.